JP7836059B2 - Zwitterions and poorly soluble substance dissolving agents - Google Patents

Description

This invention relates to zwitterions and dissolving agents for poorly soluble substances.

Despite possessing various physiological activities and other properties, substances that are poorly soluble have limited applicability. Dimethyl sulfoxide (DMSO) is commonly used as a solvent for such poorly soluble substances. However, some substances do not dissolve in DMSO, and there are concerns about the toxicity of DMSO, so new solvents are needed. Furthermore, although DMSO is used as a cryopreservative for cell preservation, it is known that cryopreserved cells can cause hypertension, nausea, and vomiting when infused into recipients or handled by those handling the cells, so new cryopreservatives for cells are needed.
Kuroda et al. at Kanazawa University have developed several zwitterions as new low-toxicity solvents (Patent Documents 1-3, Non-Patent Documents 1-4).

Japanese Patent Publication No. 2018-191623 Japanese Patent Publication No. 2022-108914 Japanese Patent Publication No. 2023-123780

Synthesis of N-oxyethylene substituted imidazolium-based zwitterions as a recyclable solvent for cellulose dissolution (Cellulose (2023) 30:87-109) Cellulose dissolution using a novel zwitterion containing oligoethers (29th Annual Meeting of the Cellulose Society) Development of low-viscosity zwitterions with flexible spacers (12th Symposium on Ionic Liquids) Development of low-viscosity zwitterions for biomass processing (2021 Japan Chemical Society Annual Meeting)

However, the aforementioned zwitterions and zwitterionic liquids were not yet fully practical because they could dissolve a limited variety of substances and were toxic to cells.
Therefore, the object of the present invention is to provide a substance that can dissolve a wide range of poorly soluble substances and has low cytotoxicity.

Therefore, the present inventors investigated the chemical structure of the previously reported zwitterions and synthesized a new zwitterion by introducing a moderately hydrophilic ether chain into the cation side chain of the zwitterion or between the anion and cation (spacer). They then investigated its solubility for poorly soluble substances and found that the zwitterion represented by the following general formula (1) can dissolve substances that could not be dissolved by existing zwitterions or zwitterionic liquids. Furthermore, they found that this zwitterion has low cytotoxicity and is useful as a cryopreservation agent for cells.

In other words, the present invention provides the following inventions [1] to [9].
[1] General formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
However, the following compounds _are defined: ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = _CH2CH2 , ^R3 = _CH2CH2 , n = 3, and B = COO- ^{; R1} = _CH3 , _R4 = _CH2CH2 , m ⁼ 1, A = imidazolium cation, _R2 = ( _{CH2 ) 1,3,4 or 5} , n = 0, and ^B = COO- ^;
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) _{1,3 or 5} , n = 0, and B = ^COO-
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 3, A = imidazolium cation, ^R2 = ( _CH2 ) _{3 or 5} , n = 0, and B = ^COO-
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = _SO3- ^.
₍ Excluding compounds _where ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = _CH2CH2 , n = 0, and B = _SO3- ^, and compounds where ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = ammonium cation, ^R2 = ( _CH2 ) _{3 ,} n = 0, and B = ^COO- .)
A zwitterion represented by .
[2] The zwitterion according to [1], wherein ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms.
[3] The zwitterion according to [1] or [2], wherein A is an imidazolium cation, an ammonium cation, a pyrazolium cation, a pyridinium cation, a pyrrolidinium cation, a morpholinium cation, or a piperidinium cation.
[4] A zwitterion according to any one of [1 ^] to [3], wherein B is an anion selected from ^-COO- , _-SO3- , and -OP=O(OH) ^O- .
[5] A zwitterion according to any of [1] to [4] that satisfies one or more conditions selected from (i) to (iii) below.
(i) ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 2 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms. (ii) ^R4 is an alkylene group having 3 to 4 carbon atoms. (iii) m is a number between 4 and 150. [6] General formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
_However , the following compounds exist: ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 1-2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO- ,
₍ Excluding compounds where ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₅ , n = 0, and B = ^COO- .)
A solvent for poorly soluble substances (excluding cellulose) containing a zwitterion represented by [a specific formula].
[7] A solvent for poorly soluble substances (excluding cellulose) as described in [6], which satisfies one or more of the following conditions selected from (i) to (iii).
(i) ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 2 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms. (ii) ^R4 is an alkylene group having 3 to 4 carbon atoms. (iii) m is a number from 4 to 150. [8] General formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
However, the compound _is defined as having ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 1 to 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO- .
A compound in which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = ₂ , A = imidazolium cation, ^R2 = ( _CH2 ) ₅ , n = 0, and B = ^COO- .
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = _SO3- ^.
₍ Excluding compounds where ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = ammonium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO-, and compounds where ^R1 = _CH3 , ^R4 = _{CH2CH2 ,} m = ₂ , A = imidazolium cation, ^R2 = _CH2CH2 , n = 0, and B = _SO3- ^. )
A cell cryopreservation agent containing a zwitterion represented by [formula].
[9] A cryopreservation agent for cells as described in [8] that satisfies one or more conditions selected from (i) to (iii) below.
(i) ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 2 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms. (ii) ^R4 is an alkylene group having 3 to 4 carbon atoms. (iii) m represents a number from 4 to 150.

The zwitterion of the present invention exhibits excellent solubility in a wide range of poorly soluble substances and is useful as a solvent for various poorly soluble substances. Furthermore, the zwitterion of the present invention has low cytotoxicity and is also useful as a cryopreservation agent for cells.

The results of cytotoxicity tests on mouse fibroblasts treated with OP3imC3C and OP3imC4S are shown. The results of cytotoxicity tests on mouse fibroblasts treated with OE9imC3C and OE9imC4S are shown. The results of cytotoxicity tests on mouse fibroblasts treated with OE2AnC2OE2OM1C and OE2MoC2OE2OM1C are shown. The results of cryopreservation tests on human breast cancer cells are shown. The results of the cryopreservation test of human kidney cells are shown. The results of cryopreservation tests on human lung cancer cells are shown. The results of the cryopreservation test of human kidney cells are shown. The results of cryopreservation tests on human lung cancer cells are shown.

In this specification, a zwitterion refers to an ion having a zwitterionic structure. Here, a zwitterion is a molecule that possesses both positive and negative charges within a single molecule, and is also called a zwitterion.
In this specification, a poorly soluble substance refers to a substance that has low solubility in a solvent such as water. A solvent for poorly soluble substances refers to an agent that dissolves poorly soluble substances. Furthermore, in this specification, poor solubility and poor dissolution are treated as synonyms.
In the present invention, a cell cryopreservation agent is an agent added when cryopreserving various types of cells, and is an additive for protecting cells during freezing and thawing.

One aspect of the present invention relates to general formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
However, the following compounds _are defined: ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = _CH2CH2 , ^R3 = _CH2CH2 , n = 3, and B = COO- ^{; R1} = _CH3 , _R4 = _CH2CH2 , m = 1, A = imidazolium cation, _R2 = ( _{CH2 ) 1,3,4 or 5} , n = 0, and ^{B =} COO- ^;
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) _{1,3 or 5} , n = 0, and B = ^COO-
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 3, A = imidazolium cation, ^R2 = ( _CH2 ) _{3 or 5} , n = 0, and B = ^COO-
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = _SO3- ^.
₍ Excluding compounds _where ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = _CH2CH2 , n = 0, and B = _SO3- ^, and compounds where ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = ammonium cation, ^R2 = ( _CH2 ) _{3 ,} n = 0, and B = ^COO- .)
It is a zwitterion represented by [formula].

The zwitterion of the present invention has a cationic moiety represented by A and an anionic moiety represented by B. The zwitterion of the present invention is characterized by the introduction of moderately hydrophilic ether chains ((OR ⁴ ) and (OR ³ )) into the cationic side chain of the zwitterion or between the anion and the cation (spacer portion). This structure is thought to significantly improve the solubility of a wide range of poorly soluble substances compared to existing zwitterionic compounds.

^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms.

"Substituted or unsubstituted" means that the hydrogen atoms of one group may or may not be substituted by another group. Here, there are no particular limitations on the substituents that can be substituted.
Furthermore, there is no particular limit to the number of substituents that can be further substituted for a single substituent; they can be appropriately selected considering the desired structure of the glycol ether. However, substitution with the same substituent is not permitted. That is, an alkyl group as a substituent will not be substituted with another alkyl group.

Examples of such substituents include halogen atoms such as fluorine, chlorine, bromine, and iodine; alkyl groups such as methyl, ethyl, tert-butyl, and dodecyl; aromatic hydrocarbon groups such as phenyl, p-tolyl, xylyl, cumenyl, naphthyl, anthuryl, and phenanthryl; alkoxy groups such as methoxy, ethoxy, and tert-butoxy; aryloxy groups such as phenoxy and p-tolyloxy; alkoxycarbonyl groups such as methoxycarbonyl, butoxycarbonyl, octyloxycarbonyl, and phenoxycarbonyl; acyloxy groups such as acetoxy, propionyloxy, methacryloyloxy, and benzoyloxy; acetyl, benzoyl, isobutylyl, and alkoxycarbonyl groups. Examples of alkyl groups include acyl groups such as liloyl, methacryloyl, and methoxalyl groups; alkylsulfanyl groups such as methylsulfanyl and tert-butylsulfanyl groups; arylsulfanyl groups such as phenylsulfanyl and p-tolylsulfanyl groups; alkylamino groups such as methylamino and cyclohexylamino groups; dialkylamino groups such as dimethylamino, diethylamino, morpholino, and piperidino groups; arylamino groups such as phenylamino and p-tolylamino groups; as well as hydroxyl, carboxyl, formyl, mercapto, sulfo, mesyl, p-toluenesulfonyl, amino, nitro, cyano, trifluoromethyl, trichloromethyl, trimethylsilyl, phosphinico, and phosphono groups. Among these, alkyl groups such as methyl, ethyl, tert-butyl, and dodecyl groups are preferred from the viewpoint of solubility.

As linear or branched saturated or unsaturated hydrocarbon groups having 1 to 20 carbon atoms, linear or branched saturated or unsaturated hydrocarbon groups having 1 to 16 carbon atoms are preferred, linear or branched saturated or unsaturated hydrocarbon groups having 1 to 12 carbon atoms are more preferred, linear or branched saturated or unsaturated hydrocarbon groups having 1 to 8 carbon atoms are even more preferred, and linear or branched saturated or unsaturated hydrocarbon groups having 1 to 6 carbon atoms are even more preferred.
Specific examples of linear or branched saturated hydrocarbon groups having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isoamyl group, tert-pentyl group, neopentyl group, n-hexyl group, 3-methylpentan-2-yl group, 3-methylpentan-3-yl group, 4-methylpentyl group, 4-methylpentan-2-yl group, 1,3-dimethylbutyl group, 3,3-dimethylbutyl group, 3,3-dimethylbutan-2-yl group, n-heptyl group, 1-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, and 1-ethylpentyl group. Tyl group, 1-(n-propyl)butyl group, 1,1-dimethylpentyl group, 1,4-dimethylpentyl group, 1,1-diethylpropyl group, 1,3,3-trimethylbutyl group, 1-ethyl-2,2-dimethylpropyl group, n-octyl group, 2-methylhexane-2-yl group, 2,4-dimethylpentan-3-yl group, 1,1-dimethylpentan-1-yl group, 2,2-dimethylhexane-3-yl group, 2,3-dimethylhexane-2-yl group, 2,5-dimethylhexane-2-yl group, 2,5-dimethylhexane-3-yl group, 3,4-dimethylhexane-3-yl group, 3,5-dimethylhexane-3-yl group, 1-methylheptyl group, 2-methylheptyl group, 5- Methylheptyl group, 2-methylheptan-2-yl group, 3-methylheptan-3-yl group, 4-methylheptan-3-yl group, 4-methylheptan-4-yl group, 1-ethylhexyl group, 2-ethylhexyl group, 1-propylpentyl group, 2-propylpentyl group, 1,1-dimethylhexyl group, 1,4-dimethylhexyl group, 1,5-dimethylhexyl group, 1-ethyl-1-methylpentyl group, 1-ethyl-4-methylpentyl group, 1,1,4-trimethylpentyl group, 2,4,4-trimethylpentyl group, 1-isopropyl-1,2-dimethylpropyl group, 1,1,3,3-tetramethylbutyl group, n-nonyl group, 1-methyloctyl group, 6-methyloctyl Examples include tyl group, 1-ethylheptyl group, 1-(n-butyl)pentyl group, 4-methyl-1-(n-propyl)pentyl group, 1,5,5-trimethylhexyl group, 1,1,5-trimethylhexyl group, 2-methyloctan-3-yl group, n-decyl group, 1-methylnonyl group, 1-ethyloctyl group, 1-(n-butyl)hexyl group, 1,1-dimethyloctyl group, 3,7-dimethyloctyl group, n-undecyl group, 1-methyldecyl group, 1-ethylnonyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, 1-methyltridecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, and n-nonadecyl group.
In particular, from a manufacturing standpoint, methyl groups, ethyl groups, isopropyl groups, n-butyl groups, isobutyl groups, n-hexyl groups, and 2-ethylhexyl groups are preferred. More preferably, from a toxicity standpoint, methyl groups, ethyl groups, isopropyl groups, n-butyl groups, and isobutyl groups are preferred.
Specific examples of linear or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms include vinyl group, 1-propenyl group, allyl group, 1-butenyl group, 3-butenyl group, isoprenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, and heptadecenyl group. Examples include the octadecenyl group (for example, the oleyl group ((Z)-octadeca-9-en-1-yl group)), the linoleoyl group ((9Z,12Z)-octadeca-9,12-dienoyl group), the α-linolenoyl group ((9Z,12Z,15Z)-octadeca-9,12,15-trienoyl group), and the γ-linolenoyl group ((6Z,9Z,12Z)-octadeca-6,9,12-trienoyl group).

As the saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 12 carbon atoms is preferred, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 8 carbon atoms is more preferred, and a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 6 carbon atoms is even more preferred.
Specific examples of saturated non-aromatic cyclic hydrocarbon groups having 3 to 20 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, norbornyl, and adamantyl groups. From a manufacturing standpoint, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups are preferred.
Furthermore, specific examples of unsaturated non-aromatic cyclic hydrocarbon groups having 3 to 20 carbon atoms include cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, 2,4-cyclopentadienyl group, cyclohexenyl group, 2,5-cyclohexadienyl group, and cyclooctenyl group.

As aromatic hydrocarbon groups having 6 to 30 carbon atoms, aromatic hydrocarbon groups having 6 to 24 carbon atoms are preferred, aromatic hydrocarbon groups having 6 to 18 carbon atoms are more preferred, and aromatic hydrocarbon groups having 6 to 10 carbon atoms are even more preferred. Specifically, phenyl group, biphenyl group, 1-naphthyl group, 2-naphthyl group, 9-anthuryl group, 9-phenanthryl group, 1-pyrenyl group, 5-naphthacenyl group, 1-indenyl group, 2-azlenyl group, 9-fluorenyl group, terphenyl group, quarterphenyl group, mesityl group, pentarenyl group, binaphthalenyl group, ternaphthalenyl group, quarternaphthalenyl group, heptarenyl group, biphenylenyl group, indacenyl group, fluoranthenyl group, acenaphthyrenyl group, aceantrilenyl group, phenalenyl group, phenylenyl group, phenylenyl group Examples include ruorenyl group, anthryl group, biantracenyl group, terantracenyl group, quarterantracenyl group, anthraquinolyl group, phenanthryl group, triphenylenyl group, pyrenyl group, chrysenyl group, naphthacenyl group, pleiadenyl group, picenyl group, perilennyl group, pentaphenyl group, pentacenyl group, tetraphenylenyl group, hexaphenyl group, hexacenyl group, rubicenyl group, coronenyl group, trinaphthyleneyl group, heptaphenyl group, heptacenyl group, pyrantrenyl group, ovalenyl group, etc. Preferably, from the viewpoint of solubility, it is a phenyl group.

As aromatic hydrocarbon-alkyl groups having 7 to 31 carbon atoms, aromatic hydrocarbon-alkyl groups having 7 to 25 carbon atoms are preferred, aromatic hydrocarbon-alkyl groups having 7 to 19 carbon atoms are more preferred, and aromatic hydrocarbon-alkyl groups having 7 to 16 carbon atoms are even more preferred. Examples include phenyl-C1-6 alkyl groups, naphthyl-C1-6 alkyl groups, anthracenyl-C1-6 alkyl groups, etc. Specifically, examples include benzyl group, phenethyl group, phenylpropyl group, phenylbutyl group, naphthylethyl group, 3-phenylpropyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 2-(1-naphthyl)ethyl group, 2-(2-naphthyl)ethyl group, 3-(1-naphthyl)propyl group, or 3-(2-naphthyl)propyl group. Among these, the benzyl group is preferred from the viewpoint of solubility.

A is the cation portion of a zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
Of these cations, imidazolium cation, ammonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, or piperidinium cation is preferred, imidazolium cation, ammonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, or piperidinium cation is more preferred, and imidazolium cation, ammonium cation, or morpholinium cation is even more preferred.

For example, a specific example of a compound of general formula (1) when A is an imidazolium cation is a compound represented by the following formula (1im). The substituent X is the same or different and represents a hydrogen atom or a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 8 carbon atoms.

Specific examples of compounds of general formula (1) when A is an ammonium cation or a morpholinium cation include compounds similarly represented by the following formulas (1An) and (1Mo).

Thus, the ether chains (OR ⁴ ) and (R ² ) that bond to the cation portion represented by A are thought to bond to the heteroatom.

^R2 represents an alkylene group having 1 to 4 carbon atoms. Specific examples of ^R2 include methylene, ethylene, propylene, trimethylene, tetramethylene, and butylene groups, with ethylene, propylene, and butylene groups being more preferred, and propylene and butylene groups being even more preferred. When the number of carbon atoms is 3 or more, hydrophobicity is improved, contributing to improved solubility of poorly soluble substances.

^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different. Similarly, ^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
Specific examples of ^R3 and ^R4 include methylene groups, ethylene groups, propylene groups, trimethylene groups, tetramethylene groups, and butylene groups, with ethylene groups, propylene groups, and butylene groups being preferred, and propylene groups and butylene groups being more preferred. When the number of carbon atoms is 3 or more, hydrophobicity is improved, which contributes to improving the solubility of poorly soluble substances.

Both m and n represent the average number of moles added, where m is a number between 1 and 150, and n is a number between 0 and 10. The average number of moles added refers to the average number of moles of oxyalkylene groups added per mole of zwitterion. Note that the average number of moles added is a number average.
m is preferably 3 to 150, more preferably 4 to 150, even more preferably 4 to 100, even more preferably 4 to 50, and still more preferably 4 to 9. When m is 4 or higher, the viscosity of the zwitterion decreases, which contributes to improving the solubility of poorly soluble substances.
n is more preferably 0 to 9, even more preferably 0 to 8, and even more preferably 0 to 6.

B is the anion portion of the zwitterion and represents an anion selected from _-OSO3- ^, _-SO3- , ^-COO- , ^-OP =O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
Of these, anions selected from ^-COO- , _-SO3- , and -OP ⁼ O(OH) ^O- are preferred, and anions selected ^{from -COO-} and _-SO3- are even more preferred.

^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms. Examples of ^R5 include a methyl group and an ethyl group.

Specific examples of zwitterions represented by general formula (1) include the compounds shown below (Table 1).

The structural formulas of compounds 5, 13, and 14 shown in (Table 1) are as follows:

The zwitterion represented by general formula (1) can be produced, for example, according to the following reaction equation.

(In the formula, R ⁶ represents an alkyl group or an aromatic hydrocarbon group, R ⁷ represents an alkyl group, a halogenoalkyl group or an aromatic hydrocarbon group, and A, B, R ^1- (OR ⁴ )mR ² , R ³ and n have the same meanings as described above.)

R ⁶ represents an alkyl group or an aromatic hydrocarbon group. Here, examples of alkyl groups include linear or branched alkyl groups having 1 to 8 carbon atoms. Specifically, methyl groups, ethyl groups, and tert-butyl groups are more preferred. Examples of aromatic hydrocarbon groups include phenyl groups, halogenophenyl groups, and nitrophenyl groups.
^R7 represents an alkyl group, a halogenoalkyl group, or an aromatic hydrocarbon group. Examples of alkyl groups include linear or branched alkyl groups having 1 to 8 carbon atoms. Specifically, methyl groups and ethyl groups are more preferred. Examples of halogenoalkyl groups include fluoroalkyl groups. Specifically, trifluoromethyl groups are examples. Examples of aromatic hydrocarbon groups include alkylphenyl groups. Specifically, p-toluene groups are examples.

Each step in the above reaction equation will be explained.
Step (1) is a step in which compound (2) and compound (3) are reacted to obtain compound (4). This step is a step in which the hydroxyl group of compound (2) is sulfonylated.
Compound (3) is a sulfonylation agent, and preferably a sulfonyl halide compound such as tosyl chloride, mesyl chloride, or trifluoromethylsulfonyl chloride is used.
This reaction is preferably carried out in the presence of a base. Examples of bases that can be used include tertiary amines such as triethylamine and 4-dimethylaminopyridine, and inorganic bases such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, Na, and sodium hydride.
The reaction can be carried out in a solvent at a temperature of 0°C to 100°C for about 1 to 40 hours. Common solvents such as halogenated hydrocarbons like dichloromethane, aromatic hydrocarbons like benzene and toluene, ethers, and acetonitrile can be used.

Step (2) is a step in which compound (4) and compound (5) are reacted to obtain compound (6). This reaction is preferably carried out in the presence of a base. Examples of bases that can be used include tertiary amines such as triethylamine and 4-dimethylaminopyridine, and inorganic bases such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, Na, and sodium hydride.
The reaction should be carried out in a solvent at a temperature of 0°C to 100°C for about 1 to 40 hours.

Step (3) is the step of reacting compound (6) and compound (7) to obtain compound (8). This reaction can be carried out in a solvent at a temperature of 0°C to 100°C for about 1 to 40 hours.
The resulting compound (8) can be neutralized by adding an anion exchange resin and converted to a zwitterion (1). As the anion exchange resin, an anion exchange resin having a quaternary ammonium group can be used.

The zwitterions represented by general formula (1) include those that are liquid at room temperature and those that are solid at 100°C, and are stable without decomposing up to temperatures above 100°C. Furthermore, they are low in toxicity, possess the property of dissolving sparingly soluble substances, and are useful as solvents for sparingly soluble substances and as cryopreservations for cells. Even solid zwitterions can become liquid by adding a small amount of water, for example, and can be used as solvents for sparingly soluble substances and as cryopreservations for cells, similar to liquid zwitterions.

Another aspect of the present invention is general formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
_However , the following compounds exist: ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 1-2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO- ,
₍ Excluding compounds where ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₅ , n = 0, and B = ^COO- .)
It is a solvent for poorly soluble substances (excluding cellulose) that contains a zwitterion represented by [the specified formula].

In the present invention, "poorly soluble substance" refers to a substance that is either completely insoluble in water or dissolves only slightly, and has a solubility in water (at 25°C) of 1% by weight or less, preferably 0.5% by weight or less, and particularly preferably 0.1% by weight or less. Such poorly soluble substances include, for example, substances that are active ingredients in pharmaceuticals, veterinary drugs, quasi-drugs, cosmetics, and pesticides (including candidate substances that can become active ingredients), food additives, biological and plant-derived substances (excluding cellulose), and include low molecular weight substances, as well as oligomers and high molecular weight substances such as oligopeptides, polypeptides, polysaccharides, DNA, and RNA.
"Poorly soluble drugs" refer to drugs that are "somewhat soluble,""poorlysoluble,""very poorly soluble," or "almost insoluble" as defined in the Japanese Pharmacopoeia. Specifically, these include antitumor agents, antibiotics, antihyperlipidemic agents, antibacterial agents, allergy treatments, antihypertensive agents, arteriosclerosis treatments, blood circulation promoters, hormones, fat-soluble vitamins, diabetes treatments, antiandrogens, cardiac stimulants, antiarrhythmics, anti-inflammatory agents, hypnotics and sedatives, tranquilizers, antiepileptics, antidepressants, gastrointestinal disease treatments, diuretics, local anesthetics, anticoagulants, and antihistamines. Examples include anti-muscarinic agents, anti-mycobacterial agents, immunosuppressants, antithyroid drugs, antiviral agents, anxiety-relieving sedatives, astringents, β-adrenergic receptor blockers, cardiomyogenic agents, contrast agents, corticosteroids, cough suppressants, diagnostic agents, diagnostic imaging agents, diuretics, dopamine agonists, lipid regulators, muscle relaxants, parasympathetic agonists, thyroid calcitonin, prostaglandins, radiopharmaceuticals, sex hormones, stimulants, appetite suppressants, sympathetic agonists, thyroid agents, vasodilators, isoflavones, xanthenes, etc.
More specifically, examples of poorly soluble substances include glycyrrhetinic acid and its salts, coumarin, ononine, liquiritin, peptides, polybutylenes such as collagen, polysaccharides such as xylan, lignin, and chloramphenicol.

Examples of antitumor agents include methotrexate, taxol, doxorubicin hydrochloride, bleomycin hydrochloride, tamoxifen, cisplatin, carboplatin, cyclosporine, HER2 inhibitors, melphalan, dacarbazine, carmofur, enocitabine, etoposide, 5-fluorouracil, mitoxantrone, mesna, dimesna, aminoglutethimide, acrolein, cyclophosphamide, lomustine, carmustine, cyclophosphamide, busulfan, para-aminosalicylic acid, mercaptopurine, tegaflu, azathioprine, vinblastine sulfate, mitomycin C, L-asparakinase, ubenimex, paclitaxel, and dorsomorphine.

Examples of antibiotics include streptomycin, chloramphenicol, gentamicin, tetracycline, penicillin, amikacin, dibekacin, bacitracin, cephalexin, nystatin, erythromycin, fradiomycin sulfate, cefmetazole, and tolnaftate.

Examples of antihyperlipidemia agents include cholestyramine, niceritrol, clinofibrate, clofibrate, fenofibrate, bezafibrate, soysterol, tocopherol nicotinate, nicomole, probucol, simvastatin, colestimide, and elastase.

Examples of antibacterial agents include chloramphenicol, rokitamycin, roxithromycin, cefatolidine, ofloxacin, ciprofloxacin hydrochloride, tosufloxacin tosylate, norfloxacin, lomefloxacin hydrochloride, pazufloxacin, cefpodoxime proxetil, midecamycin acetate, josamycin propionate, fosfomycin, or their salts.

Examples of allergy treatment agents include ebastine, mequitazine, methoxyphenamine, clemastine fumarate, cyproheptadine hydrochloride, fexofenadine hydrochloride, diphenhydramine, metodilamine, and cremisole.

Examples of antihypertensive agents include nicardipine hydrochloride, delapril hydrochloride, barnidipine hydrochloride, efonidipine hydrochloride, benidipine hydrochloride, alacepril, captopril, cilnidipine, felodipine, amlodipine besylate, nisoldipine, manidipine hydrochloride, nitrendipine, nilvadipine, trandolapril, valsartan, candesartan cilexetil, urapidil, carvedilol, prazosin hydrochloride, bunazosin hydrochloride, doxazosin mesylate, reserpine, methyldopa, guanabenz acetate, deserupidine, meptame, and meptamate.

Examples of agents used to treat arteriosclerosis include elastase, clofibrate, symfibrate, soysterol, and nicomol.

Examples of medications used to treat osteoporosis include zoledronic acid.

Examples of blood circulation-promoting agents include tocopherol acetate, tocopherol nicotinate, benzyl nicotinate, caffeine, trazoline, verapamil, cyclandelate, and acetylcholine.

As for hormone preparations, these include dexamethasone, dexamethasone acetate, betamethasone, betamethasone valerate, betamethasone dipropionate, beclomethasone propylonate, prednisolone, prednisolone valerate, prednisolone acetate, methylprednisolone, methylprednisolone acetate, hydrocortisone, hydrocortisone acetate, hydrocortisone propionate acetate, amcinonide, triamcinolone, triamcinolone acetonide, fluocinolone acetonide, estriol, fluocinonide, hexestrol, methimazole, estriol propionate, clobetazone acetate, clobetasol propionate, and testosterone propionate. Examples include testosterone enanthate, fluoxymesterone, stanolone, dromostanolone propionate, estradiol benzoate, estradiol propionate, estradiol valerate, ethinylestradiol, β-estradiol, mestranol, estriol acetate benzoate, fluorometholone, fludroxycortide, diflucortone valerate, halcinonide, progesterone, hydroxyprogesterone caproate, pregnanediol, medroxyprogesterone acetate, dimethisterone, norethisterone, allylestrenol, gestorone caproate, oxendrone, insulin, etc.

Examples of fat-soluble vitamins include vitamin A, its precursor (beta-carotene), vitamin D, vitamin E, and vitamin K.

Examples of diabetes medications include gliclazide, tolbutamide, glibenclamide, troglitazone, epalrestat, buformin, and metformin.

Examples of antiandrogen agents include gestolone caproate, osapron acetate, flutamide, oxendrone, allylestrenol, chlormadinone acetate, and bicalutamide.

Examples of cardiac stimulants include digoxin, digotoxin, and cobidecarenone.

Examples of antiarrhythmic drugs include lidocaine, bopindolol malonate, arotinolol hydrochloride, atenolol, pindolol, nadolol, propafenone hydrochloride, amiodarone hydrochloride, disopyramide, and carteolol hydrochloride.

Anti-inflammatory agents include glycyrrhetinic acid, dipotassium glycyrrhizinate, aspirin, aluminum aspirin, ibuprofen, ketoprofen, licyrrhetinic acid, salicylic acid, acetaminophen, methyl salicylate, glycol salicylate, aminopyrine, phenacetin, mefenamic acid, flufenamic acid, aluminum flufenamic acid, tolfenamic acid, acemetacin, indomethacin, alclofenac, diclofenac, ibuprofen piconol, oxyfen butazone, phenyl butazone, ketophenyl butazone, clofezone, thiaramide hydrochloride, diclofenac sodium, sulindac, naproxen, febufen, flurbiprofen, fenprofen, bufen Examples include Xexamac, mepirizole, perisoxal citrate, graphenin, bucolome, pentazocine, methiadic acid, protidic acid, pranoprofen, fenoprofen calcium, piroxicam, feprazon, fentiazac, bendazac, dimethylisopropylazulene, bufexamac, bucolome, benzidamine, tiaramide, tinoridine, ethenzamide, tenoxicam, chlortenoxicam, clidanac, naproxen, glycyrrhizin, azulene, camphor, thymol, l-menthol, sazapyrine, alclofuenac, diclofenac, suprofen, loxoprofen, diflunisal, tiaprofenic acid, oxaprozin, felbinac, etc.

Examples of hypnotic sedatives include barbiturates, amobarbital, amobarbital sodium, phenobarbital, phenobarbital sodium, secobarbital sodium, pentobarbital calcium, hexobarbital, triclophos, bromovalerylurea, glutethimid, methacarone, perlapine, nitrazepam, estazolam, flurazepam hydrochloride, flunitrazepam, and estazolam.

Examples of tranquilizers include diazepam, lorazepam, and oxazolam.

Examples of antiepileptic drugs include phenytoin, carbamazepine, phenobarbital, primidone, phenasemide, ethylphenasemide, etotoin, fen succimide, nitrazeban, and clonazeban.

Examples of antidepressants include phenelzine, imiplanin, and noxyptyline.

Examples of drugs used to treat gastrointestinal diseases include famotidine, sucralfate, aldioxa, irsoglazine maleate, metoclopramide, cimetidine, omeprazole, lansoprazole, emprostil, gefarnate, teprenone, sulpiride, trepibutone, and oxethazaine.

Examples of diuretics include spironolactone, chlorthalidone, polythiazide, triamterene, hydrochlorothiazide, and furosemide.

Examples of local anesthetics include ethyl aminobenzoate, procaine hydrochloride, lidocaine, lidocaine hydrochloride, dipcaine hydrochloride, tetracaine hydrochloride, benzyl alcohol, tacaine, bezocaine, pramoxin hydrochloride, catacaine hydrochloride, butanicaine hydrochloride, pipelocaine hydrochloride, and chlorobutanol.

Examples of anticoagulants include coumarin and heparin.

Examples of antiviral agents include acyclovir, nevirapine, zidovudine, zanamivir, oseltamivir, and favipiravir.

Examples of isoflavones include ononine, daidzein, biochanin A, glycitein, daidzin, glycitin, and genistin. Isoflavones may be aglycones or glycosides.

Examples of poorly soluble substances used in quasi-drugs or cosmetics include dl-α-tocopherol acetate, α-tocopherol (vitamin E), methyl cinnamate, ethyl cinnamate, hexyl laurate, trichlorocarbanilide, triazine, benzophenone, triazole, eugenol, isoeugenol, ethyl methylphenylglycidate, geranyl acetate, piperonal, cinnamyl acetate, decyl oleate, terpenyl acetate, anilide, cinnamide, sulfonated benzimidazole, carotene, piroctone olamine, minoxidil, phytosteside, tocopherol nicotinate, ethinylestradiol, polyporsterone, and ecdysteroids.

As a pesticide, any poorly soluble active ingredient with insecticidal, fungicidal, herbicidal, or plant growth regulating properties can be used. For example, poorly soluble insecticides include abamectin, acrinatrin, amitraz, azadirachtin, azamethiphos, azinophosmethyl, azocyclotin, methiocarb, thiodicarb, trimetacarb, etofenprox, ethylthiometone, methoxychlor, chlorpyrifosmethyl, chlorfensone, chlorfluazuron, tebufenpyrad, bensultap, bifenthrin, bromopropylate, buprofezin, carbaryl, chlorfenapyr, clofentezene, coumaphos, diazinon, cycloprothrin, cyfluthrin, β-cyfluthrin, cypermethrin, α-cypermethrin, θ-cypermethrin, deltamethrin, diafenthiuron, dicofol, diflubenzuron, and cal It can dissolve bosulfan, endosulfan, esfenvalerate, ethoxazol, phenazaquin, fenbutane oxide, phenoxycarb, fenpyroximate, fipronil, fluazuron, flucycloxuron, flufenoxuron, flubendiamide, fenthion, halofenozide, hexaflumuron, hexythiazox, hydramethylnon, metaflumizone, lufenuron, milbemectin, novaron, pentachlorophenol, pyridaben, rotenone, sulfuramide, tebufenozide, tebupyrimphos, teflubenzuron, tetrachlorvinphos, tetradiphon, benfuracarb, tolfenpyrad, triflumulon, tralomethrin, flatiocarb, etc.

Furthermore, poorly soluble bactericidal substances include: bromconazole, carpropamide, diclofen, metconazole, hexaconazole, fentin, mancozeb, maneb, diclomedin, azoxystrobin, isoprothiolane, venalaxyl, benomyl, vitertanol, captafoll, captan, carbendazim, quinomethionate, chlorothalonil, clozolinate, cyprodinil, diclofluanide, dichloran, diclosimate, diethofencarb, dimethomorph, diniconazole, dithianone, thiadinil, epoxyconazole, famoxadone, phenalimol, fenbuconazole, fenflam, fenpiclonil, fluazinam, fludioxonil, fluoro Examples include Mid, fluquinconazole, flusulfamide, flutolanil, holpet, hexachlorobenzene, imibenconazole, ipoconazole, iprodione, kresoximmethyl, mepanipyrim, mepronil, methylam, nickelbis(dimethyldithiocarbamate), nualimol, oxycopper, oxolinic acid, pencyclon, phthalide, procymidone, propineb, quintozen, sulfur, tebuconazole, tecrophthalam, technazen, tifluzamide, thiophenatemethyl, thyram, tolclophosmethyl, triadimefone, tolfluanide, triadimenol, triazoxide, trifoline, triticonazole, vinclozoline, zineb, and ziram.

Examples of poorly soluble herbicides include bromobutide, acronifen, clomethoxyfen, lactofen, promethrin, propazine, azaphenidine, tenylchlor, bifenox, sulfentrazone, pyraflufen ethyl, flumicrolacpentyl, flumioxazine, atrazine, indanophan, bensulfuron methyl, benzofenap, bromophenoxime, chlorbromulon, chlorimulon ethyl, chlornitrofen, chlorotoluron, chlortaldimethyl, clomeprop, dimuron, desmedifam, diclobenyl, diflufenican, dimeflon, dinitramine, diuron, etamethosulfuron methyl, triaziflame, phenoxapropyl ethyl, and flam Examples include propmethyl, flazasulfuron, flumetsuram, fluthiasetmethyl, flupoxam, fluridone, flurutamon, oxadiclomefone, isoproturone, isoxaben, isoxapyrhop, lenacil, linuron, mefenacet, metabenzuthiazulon, metobenzulon, naproanilide, nevron, norflurazone, oryzalin, oxadiazone, oxyfluorphen, fenmedifam, prodiamine, propizamide, pyrazolinate, pyrazosulfuron ethyl, pyributicarb, quinchlorac, quizaropop ethyl, limsulfuron, siduron, simazine, terbutyrazine, terbutrin, thiazopyr, tracoxidim, trietadine, etc.

Examples of poorly soluble plant growth regulators include cyclanilide, flumetraline, 6-benzylaminopurine, forchlorfenuron, inabenfide, 2-(1-naphthyl)acetamide, paclobutrazol, N-phenylphthalamidic acid, tidiazuron, and uniconazole.

Furthermore, examples of poorly soluble substances used as food additives include glycyrrhizin, L-ascorbic acid stearate, benzoic acid, isoeugenol, ergocalciferol (vitamin D2), eugenol, butyl parahydroxybenzoate, isopropyl parahydroxybenzoate, β-carotene, citronellyl formate, cholecalciferol (vitamin D3), propyl gallate, folic acid, lecithin, cinnamyl acetate, phenethyl acetate, ethyl cinnamate, dibutylhydroxytoluene, allyl hexanoate, methyl β-methyl ketone, riboflavin butyrate, and dl-α-tocopherol.

Examples of poorly soluble plant-derived substances include xylan, lignin, chondroitin sulfate, and glucomannan.

Examples of polypeptides include collagen, casein, albumin, elastin, and silk protein.

Examples of poorly soluble polysaccharides include chitin and chitosan.

The solvent for poorly soluble substances of the present invention, although speculative and not limited thereto, can dissolve various poorly soluble substances with low polarity, i.e., hydrophobic tendencies, by introducing medium- and low-polarity groups into the zwitterion of the present invention. Furthermore, although speculative and not limited thereto, it is thought that the solubility for poorly soluble substances can be further improved by increasing the proportion of medium- and low-polarity groups.

The zwitterion of the present invention further improves the solubility of sparingly soluble substances when it satisfies one or more of the following conditions (i) to (iii).
(i) ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 2 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms. (ii) ^R4 is an alkylene group having 3 to 4 carbon atoms. (iii) m is a number between 4 and 150. The reason why the solubility of poorly soluble substances improves is speculative and not limited to this, but it is thought that hydrophobic interactions improve when any one or more of the above conditions (i) to (iii) are met.

When dissolving poorly soluble substances, they can be dissolved at temperatures ranging from -10°C to 100°C, further from 10°C to 80°C, and even further from 10°C to 30°C. Generally, higher temperatures are better from the standpoint of solubility, but some poorly soluble substances may lose their activity at such temperatures. Therefore, by using the zwitterion of the present invention as a solvent, dissolution is possible even at temperatures lower than such high temperatures.

The amount of sparingly soluble substance dissolved by the zwitterion of the present invention is not particularly limited, but in some cases 0.00001 to 10 parts by mass of the sparingly soluble substance can be dissolved per 100 parts by mass of the zwitterion of the present invention, and in some cases 0.0001 to 5 parts by mass can be dissolved, and in some cases 0.001 to 1 part by mass can be dissolved.
Since pharmaceuticals are often effective even at very low concentrations, even if only a small amount of a poorly soluble substance is dissolved, it can be used as a pharmaceutical product and obtain its medicinal effects, making it very useful.

In addition to the aforementioned zwitterions, additives suitable for the application of the poorly soluble substance may be added to the solvent for the poorly soluble substance. Examples of such additives include water, alcohols such as ethanol, polyols including diols and triols, sugars, salts, polymers such as polyethylene glycol and polyvinyl alcohol, other zwitterions, ionic liquids, zwitterionic polymers, ionic liquid polymers, amino acids, oils and fats, surfactants, and organic solvents such as methanol, dimethyl sulfoxide, and dimethylformamide that can be used in cell or animal-related experiments.

In the dissolving agent for poorly soluble substances obtained by adding the above-mentioned additive to the zwitterion of the present invention, the concentration of the zwitterion is not particularly limited, but can be 0.1 to 100% by mass, moreover 1 to 90% by mass, particularly 20 to 80% by mass, and moreover 30 to 70% by mass.

Another aspect of the present invention is general formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
However, the compound _is defined as having ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 1 to 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO- .
A compound in which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = ₂ , A = imidazolium cation, ^R2 = ( _CH2 ) ₅ , n = 0, and B = ^COO- .
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = _SO3- ^.
₍ Excluding compounds where ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = ammonium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO-, and compounds where ^R1 = _CH3 , ^R4 = _{CH2CH2 ,} m = ₂ , A = imidazolium cation, ^R2 = _CH2CH2 , n = 0, and B = _SO3- ^. )
This is a cell cryopreservation agent containing a zwitterion represented by [the formula shown].

The origin of cells that can be used for cryopreservation is not particularly limited, and examples include animal cells, insect cells, plant cells, yeast, and bacteria. Animal cells include those from humans, mice, rats, monkeys, pigs, dogs, sheep, and goats. Bacteria include lactic acid bacteria, Escherichia coli, Bacillus subtilis, and cyanobacteria.
Furthermore, the type of cells is not particularly limited and can be appropriately selected from, for example, a group consisting of pluripotent stem cells, tissue stem cells, somatic cells, and germ cells. Here, "pluripotent stem cells" is a general term for stem cells that have the ability to differentiate into cells of any tissue (pluripotency), and examples include embryonic stem cells (ES cells), induced pluripotent stem cells (iPS cells), embryonic germ stem cells (EG cells), germ stem cells (GS cells), etc. Preferably, ES cells or iPS cells are used.
Furthermore, "tissue stem cells" refer to stem cells whose differentiated cell lineage is limited to a specific tissue, but which possess the ability to differentiate into a variety of cell types (pluripotency). Examples include hematopoietic stem cells in the bone marrow, neural stem cells, liver stem cells, and skin stem cells.
"Somatic cells" refer to cells other than germ cells that make up a multicellular organism. Preferably, these include osteoclasts, fibroblasts, hepatocytes, pancreatic cells, muscle cells, osteocytes, osteoblasts, chondrocytes, adipocytes, skin cells, kidney cells, lung cells, lymphocytes, erythrocytes, leukocytes, monocytes, macrophages, etc.
"Germ cells" include gametes for sexual reproduction, namely eggs, oocytes, sperm, spermatophores, and spores for asexual reproduction.
The cells may be selected from a group consisting of sarcoma cells, cell lines, and transformed cells. "Sarcoma" refers to cancer that arises in connective tissue cells derived from non-epithelial cells such as bone, cartilage, fat, muscle, and blood, and includes soft tissue sarcomas and malignant bone tumors. Sarcoma cells are cells derived from sarcomas. "Cell lines" refer to cultured cells that have been maintained outside the body for a long period of time, possess certain stable properties, and are capable of semi-permanent subculturing. Examples include PC12 cells (derived from rat adrenal medulla), CHO cells (derived from Chinese hamster ovaries), HEK293 cells (derived from human fetal kidney), HL-60 cells (derived from human leukocytes), and HeLa cells (derived from human cervical cancer). "Transformed cells" refer to cells whose genetic properties have been altered by introducing nucleic acids (DNA, etc.) from outside the cell. Transformation of animal cells, plant cells, and bacteria is carried out using conventionally known methods.
Furthermore, the culture medium may include feeder cells as needed, which are used to create an environment necessary for cell proliferation and differentiation when culturing ES cells or iPS cells. Examples of feeder cells include mouse fibroblasts. These feeder cells can be treated beforehand to prevent proliferation by gamma irradiation or antibiotics.

The concentration of the zwitter ion of the present invention as a cryopreservative for cells is preferably 0.1 to 70% by weight, more preferably 1 to 50%, and even more preferably 3 to 30% relative to the total amount of the cryopreservative for cells.
The cell cryopreservation agent of the present invention prevents the formation of ice crystals by the zwitter ions of the present invention, thereby preventing the physical destruction of cells.

The cryopreservative of the present invention may also contain cell culture medium components in addition to the zwitterions of the present invention. In this case, the cryopreservative of the present invention functions as a culture medium composition or a culture composition. Examples of cell culture medium components include cell culture medium components, specifically inorganic salts, buffers, carbohydrates, vitamins, proteins, peptides, fatty acids, lipids, trace elements, serum, hormones, growth factors, signaling molecules, antibiotics, DMSO, etc.

When the cryopreserving agent of the present invention is used as a culture medium composition or culture composition, the content of the zwitterion of the present invention is not limited, but is preferably 1 to 40% by mass, more preferably 3 to 25% by mass, and even more preferably 10 to 15% by mass. If the content of the zwitterion exceeds 40% by mass, the cell viability may decrease. However, it is possible to increase the cell viability by using the slow freezing method or rapid freezing method described below.

By using the cryopreservative of the present invention, the viability of cells can be improved after freezing a cell dispersion by slow freezing or rapid freezing and then thawing. Here, the cell freezing conditions in the slow freezing method can be set as appropriate in accordance with conventional conditions. Specifically, in the slow freezing method, for example, the cells can be cooled to 0 to -200°C at a cooling rate of -0.1 to -15°C/min. In the rapid freezing method, for example, the cooling rate can be set to -15 to -20000°C/min and the cooling temperature to be in the range of 0 to -200°C.
For thawing cryopreserved cells, it is preferable to quickly transfer the ampoule containing the frozen cells to a 37°C water bath. Transfer the contents of the ampoule to a sterile tube using a pipette. Then, gradually add preheated culture medium with appropriate supplements. Measure the viable cell density using trypan blue. Transfer an appropriate amount of cell suspension to a flask and seed at the cell density recommended on the cell line datasheet.

The zwitterions used in the cryopreservation agent for cells of the present invention are preferably those that satisfy one or more of the following conditions (i) to (iii).
(i) ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 2 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms. (ii) ^R4 is an alkylene group having 3 to 4 carbon atoms. (iii) m is a number between 4 and 150.

The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

( ^1H -NMR)
^1H -NMR was measured using a JEOL Ltd. ECX400II (external magnetic field 400 MHz). The deuterated solvents used were deuterated chloroform, deuterated DMSO, or deuterated water.

(Synthesis Example 1)
(1) Synthesis of the zwitterion iBuOE2imC3C 250 g of diethylene glycol monoisobutyl ether (manufactured by Nippon Emulsifier Co., Ltd.), 700 g of toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 154 g of NaOH (manufactured by Tosoh Corporation) were added and mixed. 352.2 g of p-tosyl chloride (manufactured by TCI) was added and the mixture was stirred at 30°C for 2 hours. After the reaction, deionized water was added and the mixture was separated to obtain diethylene glycol monoisobutyl ether p-toluenesulfonate.
93.2 g of imidazole (manufactured by Fujifilm Wako Pure Chemical Industries), 932 g of tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries), and 136.9 g of NaOH were added and mixed. 433.2 g of diethylene glycol monoisobutyl ether p-toluenesulfonate was added and the mixture was stirred at 60°C for 7 hours. The resulting reaction solution was filtered to obtain diethylene glycol monoisobutyl ether imidazole.
113.5 g of diethylene glycol monoisobutyl etherimidazole and 58.4 g of ethyl-4-bromobutyrate (manufactured by TCI) were mixed and refluxed at 80°C for 6 hours. After washing with diethyl ether, the mixture was mixed with an anion exchange resin, filtered, and the solvent was removed by vacuum distillation to obtain iBuOE2imC3C.
^1H -NMR (400MHz, CHLOROFORM-D) δ 10.76 (s, 1H), 7.55 (s, 1H), 7.29 (s, 1H), 4.62-4.64 (m, 2H), 4.36-4.39 (m, 2H), 3.85-3.87 (m, 2H) ), 3.54-3.64 (m, 4H), 3.19-3.21 (dd, 2H), 2.14-2.24 (m, 4H), 1.80-1.90 (m1H), 0.88-0.90 (d, 6H)

(Synthesis Example 2)
(2) Synthesis of the zwitterion iBuOE2imC4S 89.0 g of diethylene glycol monoisobutyl etherimidazole obtained in the same manner as in Synthesis Example 1 and 62.9 g of 1,4-butanesultone (manufactured by TCI) were mixed and refluxed at 80°C for 6 hours. After washing with diethyl ether, the solvent was removed by vacuum distillation to obtain iBuOE2imC4S.
^1H -NMR (400MHz, CHLOROFORM-D) δ 9.66 (s, 1H), 7.62 (s, 1H), 7.58 (s, 1H), 4.47-4.50 (m, 2H), 4.35-4.37 (m, 2H), 3.85-3.87 (m, 2H), 3.62-3.65 (m, 2H) , 3.53-3.55 (m, 2H), 3.19-3.20 (d, 2H), 2.84-2.88 (m, 2H), 2.08-2.12 (m, 2H), 1.81-1.89 (m, 3H), 0.88-0.89 (d, 6H)

The following compounds were prepared in the same manner as in Synthesis Examples 1 and 2.
(3) Synthesis of OE9imC3C (Synthesis Example 3)
^1H -NMR (400MHz, DMSO-D6) δ 9.42 (s, 1H), 7.82 (s, 1H), 7.75 (s, 1H), 4.37-4.39 (m, 2H), 4.18-4.21 (m, 2 H), 3.78-3.80 (m, 2H), 3.41-3.56 (m, 32H), 3.24 (s, 3H), 1.87-1.95 (m, 4H)

(4) Synthesis of OE9imC4S (Synthesis Example 4)
^1H -NMR (400MHz, CHLOROFORM-D) δ 9.74 (s, 1H), 7.59 (s, 1H), 7.54 (s, 1H), 4.44-4.51 (m, 2H), 4.34-4.37 (m, 2H), 3.50- 3.95 (m, 34H), 3.38 (s, 3H), 2.87-2.91 (m, 2H), 2.10-2.13 (m, 2H), 1.86-1.90 (m, 2H)

(5) Synthesis of OE4imC3C (Synthesis Example 5)
^1H -NMR (400MHz, CHLOROFORM-D) δ 10.47 (s, 1H), 7.58 (s, 1H), 7.37 (s, 1H), 4.57-4.59 (m, 2H), 4.34-4.37 (m, 2H), 3.85-3.87 (m, 2H), 3.47-3.72 (m, 12H), 3.36 (s, 3H), 2.14-2.23 (m, 4H)

(6) Synthesis of OE4imC4S (Synthesis Example 6)
^1H -NMR (400MHz, CHLOROFORM-D) δ 9.65 (s, 1H), 7.62 (s, 1H), 7.60 (s, 1H), 4.47-4.49 (m, 2H), 4.33-4.36 (m, 2H), 3.85-3.87 (m, 2 H), 3.49-3.72 (m, 12H), 3.34 (s, 3H), 2.84-2.89 (t, 2H), 2.07-2.12 (m, 2H), 1.84-1.90 (m, 2H)

(7) Synthesis of OP3imC3C (Synthesis Example 7)
^1H -NMR (400MHz, CHLOROFORM-D) δ 10.51-10.58 (m, 1H), 7.55-7.71 (m, 1H), 7.33-7.40 (m, 1H), 4.90-5.10 (m, 1H), 4.38- 4.41 (m, 4H), 3.29-3.88 (m, 9H), 2.14-2.26 (m, 4H), 1.59-1.62 (m, 3H), 1.06-1.14 (m, 6H)

(8) Synthesis of OP3imC4S (Synthesis Example 8)
^1H -NMR (400MHz, DMSO-D6) δ 9.24 (s, 1H), 7.87 (s, 1H), 7.81 (s, 1H), 4.59-4.70 (m, 1H), 4.17-4.22 (m, 2H), 3.01-3 .83 (11H), 2.44-2.51 (m, 4H), 1.85-1.93 (m, 2H), 1.45-1.59 (m, 6H), 0.94-1.04 (m, 3H)

(9) Synthesis of BzOE1imC3C (Synthesis Example 9)
^1H -NMR (400MHz, DMSO-D6) δ 9.89 (s, 1H), 7.85 (s, 1H), 7.80 (s, 1H), 7.20-7.32 (m, 5H), 4.45-4.48 (m, 4H), 4.18-4.20 (m, 2H), 3.73-3.77 (m, 2H), 1.82-1.93 (m, 4H)

(10) Synthesis of PhOE1imC3C (Synthesis Example 10)
^1H -NMR (400MHz, DMSO-D6) δ 9.90 (s, 1H), 7.88 (s, 1H), 7.85 (s, 1H), 7.22-7.26 (m, 2H), 6.88-6.94 (m, 3H) , 4.62-4.64 (m, 2H), 4.34-4.36 (m, 2H), 4.18-4.21 (m, 2H), 1.82-1.94 (m, 4H)

(11) Synthesis of PhOE1imC4S (Synthesis Example 11)
^1H -NMR (400MHz, DMSO-D6) δ 9.30 (s, 1H), 7.83 (s, 1H), 7.80 (s, 1H), 7.25-7.30 (m, 2H), 6.92-6.93 (m, 3H), 4.57-4.60 (m, 2H) , 4.34-4.36 (m, 2H), 4.19-4.22 (m, 2H), 2.43-2.48 (m, 2H), 1.84-1.91 (m, 2H), 1.50-1.58 (m, 2H)

(12) Synthesis of OE2imC3C (Synthesis Example 12)
The synthesis method was carried out in reference to Japanese Patent No. 7233669.
^1H -NMR (400MHz, DMSO-D6) δ 9.49 (s, 1H), 7.78 (s, 1H), 7.70 (s, 1H), 4.29-4.35 (m, 2H), 4.10-4.18 (m, 2H), 3.70 -3.77 (m, 2H), 3.34-3.52 (m, 4H), 3.16 (s, 3H), 1.80-1.89 (m, 2H), 1.71-1.77 (m, 2H)

(13) Synthesis of OE2AnC2OE2OM1C (Synthesis Example 13)
500 g of dimethylaminoethoxyethanol (manufactured by Nippon Emulsifier Co., Ltd.), 700 g of toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 345 g of NaOH (manufactured by Tosoh Corporation), and 15 g of tetrabutylammonium bromide (manufactured by TCI Corporation) were added to a 3 L autoclave and mixed. 209 g of methyl chloride (manufactured by Shin-Etsu Chemical Co., Ltd.) was injected under pressure at 30°C over 2 hours, and the mixture was reacted for 24 hours. After the reaction, deionized water was added to separate the layers, and the toluene layer was distilled to obtain N-methoxyethoxyethyl-N,N-dimethylamine.
20 g of 2-(2-(2-(2-(tosyloxy)ethoxy)ethoxy)ethoxy)acetic acid (manufactured by Sigma-Aldrich), 52 g of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries), and 0.2 g of concentrated sulfuric acid (manufactured by Fujifilm Wako Pure Chemical Industries) were added and stirred at 80°C for 7 hours. Toluene and saturated saline solution were added to the resulting reaction mixture to separate the layers, and the resulting toluene layer was concentrated to obtain 2-(2-(2-(2-(tosyloxy)ethoxy)ethoxy)ethoxy)ethyl acetate.
5 g of N-methoxyethoxyethyl-N,N-dimethylamine and 13 g of 2-(2-(2-(2-(tosyloxy)ethoxy)ethoxy)ethoxy)ethyl acetate were mixed and refluxed at 80°C for 6 hours. After washing with diethyl ether, the mixture was mixed with an anion exchange resin, filtered, and the solvent was removed by vacuum distillation to obtain OE2AnC2OE2OM1C.
^1H -NMR (400MHz, CHLOROFORM-D) δ 4.00-4.03 (m, 2H), 3.93-3.97 (m, 2H), 3.86-3.92 (m, 4H), 3.82-3.86 (m, 2H), 3.60-3.70 (m, 10H), 3.50-3.53 (m, 2H), 3.36-3.40 (s, 6H), 3.34-3.36 (s, 3H)

(14) Synthesis of OE2MoC2OE2OM1C (Synthesis Example 14)
18 g of morpholine (manufactured by Nippon Emulsifier Co., Ltd.), 21 g of NaOH (manufactured by Tosoh Corporation), and 53 g of tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and mixed. 40 g of 1-bromo-2-(2-methoxyethoxy)ethane (manufactured by TCI Corporation) was added dropwise at 60°C for 1 hour, and the mixture was reacted for 24 hours. After filtering the reaction mixture, the solvent was removed by distillation under reduced pressure to obtain N-methoxyethoxyethylmorpholine.
13 g of ethyl 2-(2-(2-(2-(tosyloxy)ethoxy)ethoxy)ethoxy) prepared in the same manner as in Synthesis Example 13 was mixed with 5 g of N-methoxyethoxyethyl morpholine and refluxed at 80°C for 6 hours. After washing with diethyl ether, the mixture was mixed with an anion exchange resin, filtered, and the solvent was removed by vacuum distillation to obtain OE2MoC2OE2OM1C.
^1H -NMR (400MHz, WATER-D2) δ 4.06-4.10 (m, 4H), 3.96-4.00 (m, 4H), 3.94-3.96 (s, 2H), 3.87-3.92 (m, 4H), 3.66-3.74 (m, 12H), 3.61-3.65 (m, 4H), 3.38-3.39 (s, 3H)

(Solubility test)
Zwitterion solutions, water, and DMSO were prepared by adjusting the concentration of the zwitterion of the present invention (Examples 1-13) or OE2imC3C (Comparative Examples 1-2) with deionized water to the concentrations listed in Tables 2 and 3. The sparingly soluble substances listed in Tables 2 and 3 were then dissolved in each solution. Specifically, the solutions were stirred overnight at 30°C or 80°C, and immediately afterward, the results were visually inspected. The concentration of the sparingly soluble substances was adjusted to the concentrations (wt%) listed in Tables 2 and 3 relative to the zwitterion solution, water, or DMSO for the tests.
Dissolution criteria ○: It can be confirmed that some or all of the substance has dissolved. ×: It cannot be confirmed that any of the substance has dissolved. The results are shown in Tables 2 and 3.

(Cytotoxicity test)
Cells (mouse fibroblasts: mNF) were cultured at 10,000 cells/well in 96-well plates and then cultured for approximately 24 hours. Zwitterionic solutions were added to the culture medium (DMEM/FBS/penicillin-streptomycin/amphotericin B) to achieve zwitterionic concentrations of 2 wt%, 5 wt%, or 10 wt%. After culturing the cells for 24 hours, cell viability was investigated using CellTiter 96 ^™ Aqueous One Solution. Mouse fibroblasts (mNF) (Mouse Normal Fibroblasts) were established from C57BL/6-EGFP mice.
As a result, as shown in Figures 1 to 3, the zwitterion of the present invention exhibits weak cytotoxicity.

(Freezing and storage test)
(a) Preparation of cryopreservation solution A cryopreservation solution having the following composition was prepared.
Cryopreservation solution:
• CultureSure® cryopreservation solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・10% by weight OP3imC3C (Synthesis Example 7)/H ₂ O (ultra pure water)
・10% by weight OP3imC4S (Synthesis Example 8)/H ₂ O (ultra pure water)
・10% by weight OE9imC3C (Synthesis Example 3)/H ₂ O (ultrapure water)
・10% by weight OE9imC4S (Synthesis Example 4)/H ₂ O (ultra pure water)
・10% by weight iBu-OE2imC4S (Synthesis Example 2)/H ₂ O (ultrapure water)
Synthesis of 10 wt% OE2AnC2OE2OM1C (Synthesis Example 13) / _H2O (ultrapure water)
Synthesis of 10 wt% OE2MoC2OE2OM1C (Synthesis Example 14) / _H2O (ultrapure water)

(b) Cryopreservation of cells The cells to be cryopreserved (human breast cancer cells: MDA-MB-231, human kidney cells: BOSC, human lung cancer cells: PC9) were recovered by centrifugation using trypsin treatment, diluted in Dulbecco's modified Eagle medium (DMEM), and the cell concentration was measured for each.
Next, 1 ml of each cell was dispensed into 1.5 ml tubes to obtain 1.0 × ^10⁶ cells, centrifuged, and then suspended in 100 μl of the above cryopreservation solution. Finally, the cells were frozen using the Mr. Frosty® cell freezing container at a cooling rate of -1°C/min and a cooling temperature of -85°C.
Human breast cancer cells (MDA-MB-231) were obtained from Professor Erik Sahai (The Francis-Crick Institute, UK). Human kidney cells were obtained from Professor Erik Sahai of the Francis-Crick Institute, UK.

(c) Thawing of cells and measurement of viable cell count Thawing was performed by adding 1 ml of culture medium to the cryopreserved vial, and the supernatant was removed by centrifugation. Subsequently, the cells obtained by centrifugation were resuspended in the culture medium and the number of viable cells was measured. Cell viability is the ratio (%) of the number of viable cells after thawing to the total number of viable cells after thawing and the number of dead cells before freezing, as shown in the formula below. The cell recovery rate is calculated by dividing the number of viable cells after thawing by the number of cells before freezing, which is 1.0 × ^10⁶ (*10⁶), and multiplying by 100.

As shown in Figures 4 to 8, cells surviving after freezing and thawing were observed, confirming the cryoprotective effect. Furthermore, as shown in Figure 5, the cell survival rate after freezing and thawing exceeded 30%, and the cell recovery rate exceeded 15%, confirming its effectiveness as a cryopreservation agent.

Claims (9)

General formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
However, the compound is _{defined as having} ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = _CH2CH2 , ^R3 = _CH2CH2 , n = 3, and ^B = COO-.
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 1, A = imidazolium cation, ^R2 = ( _CH2 ) _{1,3,4 or 5} , n = 0, and B = ^COO-
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) _{1,3 or 5} , n = 0, and B = ^COO-
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 3, A = imidazolium cation, ^R2 = ( _CH2 ) _{3 or 5} , n = 0, and B = ^COO-
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0 , and B = _SO3- ^.
Compounds in which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = ₂ , A = ammonium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO- , and
(Excluding compounds in which the substituent of R1 is a (meth)acryloyl group or ^a (meth)acryloyloxy group .)
A zwitterion represented by . The zwitterion according to claim ¹ , wherein R1 is a linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms. The zwitterion according to claim 1, wherein A is an imidazolium cation, an ammonium cation, a pyrazolium cation, a pyridinium cation, a pyrrolidinium cation, a morpholinium cation, or a piperidinium cation. The zwitterion according to claim 1, wherein B is an anion selected from ^-COO- , _-SO3- , and -OP=O(OH) ^{O- .} A zwitterion according to any one of claims 1 to 4, satisfying one or more conditions selected from (i) to (iii) below.
(i) ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 2 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms. (ii) ^R4 is an alkylene group having 3 to 4 carbon atoms. (iii) m is a number between 4 and 150. General formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
However, the compound _is defined as having ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 1 to 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO- .
Compounds in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₅ , n = 0, and B = ^COO- , and
(Excluding compounds in which the substituent of R1 is a (meth)acryloyl group or ^a (meth)acryloyloxy group .)
A solvent for poorly soluble substances (excluding cellulose) containing a zwitterion represented by [a specific formula]. A solvent for poorly soluble substances (excluding cellulose) according to claim 6, satisfying one or more conditions selected from (i) to (iii) below.
(i) ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 2 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms. (ii) ^R4 is an alkylene group having 3 to 4 carbon atoms. (iii) m represents a number from 4 to 150. General formula (1)

( ^R1 represents a substituted or unsubstituted linear or branched saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms)
A is the cation portion of the zwitterion, and represents a cation selected from imidazolium cation, phosphonium cation, ammonium cation, sulfonium cation, pyrazolium cation, pyridinium cation, pyrrolidinium cation, morpholinium cation, cyclopropenilium cation, and piperidinium cation.
^R2 represents an alkylene group having 1 to 4 carbon atoms.
^R3 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
^R4 represents an alkylene group having 1 to 4 carbon atoms, either identical or different.
m represents a number between 1 and 150.
n represents a number between 0 and 10.
B is the anion part of the zwitterion, and represents an anion ^selected from _-OSO3- ^, _-SO3- , ^-COO- , -OP=O(H) ^O- , -OP=O( _CH3 ) ^O- , -OP=O( ^OR5 ) ^O- , and -OP=O(OH) ^O- .
^R5 represents an alkyl group which may have a heteroatom with 1 to 8 carbon atoms.
However, the compound _is defined as having ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 1 to 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO- .
A compound in which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = ₂ , A = imidazolium cation, ^R2 = ( _CH2 ) ₅ , n = 0, and B = ^COO- .
A compound in _which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = 2, A = imidazolium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = _SO3- ^.
Compounds in which ^R1 = _CH3 , ^R4 = _CH2CH2 , m = ₂ , A = ammonium cation, ^R2 = ( _CH2 ) ₃ , n = 0, and B = ^COO- , and
(Excluding compounds in which the substituent of R1 is a (meth)acryloyl group or ^a (meth)acryloyloxy group .)
A cell cryopreservation agent containing a zwitterion represented by [formula]. A cryopreservative for cells according to claim 8 that satisfies one or more conditions selected from (i) to (iii) below: (i) ^R1 is a linear or branched saturated or unsaturated hydrocarbon group having 2 to 20 carbon atoms, a saturated or unsaturated non-aromatic cyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic hydrocarbon-alkyl group having 7 to 31 carbon atoms; (ii) ^R4 is an alkylene group having 3 to 4 carbon atoms; (iii) m is a number from 4 to 150.